X Journal of Agricultural Research voi. iv 



A New Wheat Thrips 



Page 

 Plate XXX. Fig. i. — Prosopothrips cognatus: Egg. Fig. 2. — Prosopothrips 



cognahis: Larva. Fig. 3. — Prosopothrips cognaUis: Adult. Fig. 4. — Wheat 



leaves showing injury by Prosopothrips cognatus 224 



Cytological Studies of Azotobacter Chroococcum 



Plate XXXI. Azotohacter chroococcum: Fig. i. — Vital-stained preparation 3 7 days 

 old. Fig. 2. — An i8-hour-old culture stained by the Guignard stain, show- 

 ing strongly dyed protoplasmic granules. Fig. 3. — A 65-hour-old culture 

 stained by the Guignard method. Fig. 4. — A 9-day-old culture stained by 

 the Guignard method. Fig. 5. — A 65-hour-old culture stained progressively 

 by the Heidenhain method, showing some empty sheaths of the peculiar 

 zooglea masses detected by Beijerinck and Krzemieniewsky. Fig. 6. — An 

 i8-hoiu:-old culture on mannit agar, showing the life cycle of the organism. 

 Fig. 7. — An i8-hoiir-old cultiu-e on mannit agar, showing the life cycle 

 of the organism. Fig. 8 and 8a. — Cells drawn from an i8-hour-old culture 

 on mannit agar 240 



Plate XXXII. Azotobacter chroococcum: Cells drawn at random from a 65- 

 hour-old culture on mannit agar 240 



Plate XXXIII. Azotobacter chroococcum: Fig. i. — Photomicrograph of a 65-hour- 

 old culture stained by the Guignard method. Fig. 2, 3. — Photomicrograph 

 of a 65-hour-old culture stained by the Heidenhain method. Fig. 4.— 

 Photomicrograph of a 2-day-old culture stained with methylene blue 240 



A New Leaf and Twig Disease of Picea Engelmanni 



Plate XXXIV. Fig. i. — .4, Neopeckia coulteri, ascus with mature spores; 

 B, Herpotrichia nigra, ascus with mature spores; C, Herpotrichia quinnuesep- 

 tata, ascus with mature spores. Fig. 2. — Branch of Picea engelmanni 

 infected with Herpotrichia quinqueseptata 254 



Some Sugar-Cane Root-Boring Weevils of the West Indies 



Plate XXXV. Varieties of the sugar-cane root borer (Diaprepes spengleri): 

 Fig. I. — Variety marginatus, female from St. Croix. Fig. 2. — Variety 

 comma, male from Porto Rico. Fig. 3. — Variety spengleri, male from Porto 

 ' Rico 264 



Plate XXXVI. Fig. i. — Diaprepes spengleri, -vanety abbreviaius, icmale from 

 Porto Rico. Fig. 2. — Diaprepes famelicus , male from St. Kitts. Fig. 3. — 

 Diaprepes spengleri denudatus, new variety, male from Guadeloupe 264 



Plate XXXVII. Diaprepes spengleri, \anety festivus: Fig. i. — Female from 



Barbados. Fig. 2 — Larva from Barbados 264 



Plate XXXVIII. Fig. i. — Diaprepes spengleri, variety festivus: A, Face of 

 larva; B, maxilla of larva; C, thoracic spiracle of larva; D, third abdominal 

 spiracle of larva; E, last abdominal segments, ventral view; F, egg. Fig. 

 2. — Diaprepes spengleri, variety spengleri: A, Pupa, ventral view; B, mouth 

 parts of pupa; C, mesonotum, metanotum, and first abdominal segment; 

 D, ventral view of part of the seventh, and the eighth, ninth, and tenth 

 segments; E, dorsal view of seventh, eighth, and ninth segments 264 



A Contribution to the Life History op Spongospora Subterranea 



Plate XXXIX. Spongospora subterranea: Fig. i. — A small portion of a spore 

 ball, showing the manner in which the spores germinate. Fig. 2. — A por- 

 tion of a spore ball and a small colony of amoebae that have been set free by 



